Carson Pazdan Biomedical Engineer
Projects / Leadership

Duke eNable Team Lead

Led design on a modular prosthetic arm: one custom-fitted socket with swappable twist-lock tools, shared to eNable's open library.

Context
Duke eNable chapter
Role
Team lead
Dates
Oct 2022 – Dec 2025
Team
~10 students

At a Glance

  • What: A 3D-printed prosthetic arm for a high school student with a limb difference, built around a modular attachment system so one custom-fitted socket can take many interchangeable tools.
  • My role: Team lead. I came up with the modular concept, designed the attachment interface and three of the attachments, and led a rotating team of about 10 students through design and testing.
  • Output: Our attachments were shared to eNable's open-source library, so other chapters can adopt the swap-and-lock system.

The Idea: One Socket, Many Tools

The custom-fitted socket with an attachment locked in (left), and exploded to show the twist-lock base and retaining clip (right)The custom-fitted socket with an attachment locked in (left), and exploded to show the twist-lock base and retaining clip (right)
Fig. 1The custom-fitted socket with an attachment locked in (left), and exploded to show the twist-lock base and retaining clip (right).

Our first design was a traditional 3D-printed hand, opened and closed by strings driven by wrist movement. It worked, but a single hand can't do everything a person wants to do. I proposed separating the part that has to be custom-fitted (the socket) from the part that does the work (the tool). Each attachment shares a common tabbed base that locks into the socket with a twist and is held by a retaining clip, so the user can swap tools without refitting the arm.

Attachments

Attachments on the shared twist-lock base: the hook, the drumstick holder, and a representative flat attachmentAttachments on the shared twist-lock base: the hook, the drumstick holder, and a representative flat attachmentAttachments on the shared twist-lock base: the hook, the drumstick holder, and a representative flat attachment
Fig. 2Attachments on the shared twist-lock base: the hook, the drumstick holder, and a representative flat attachment.

The team's library included the original string-driven hand, a fork, and more. I designed three: the hook, a drumstick holder, and a guitar pick holder.

Load testing: We tested the hook by hanging a bucket from it and adding sand until it failed. It held 10 lb and failed at roughly 11.2 lb.

Why Modular Worked Beyond One User

  • It scales across eNable. eNable is an open-source effort to 3D-print prosthetics, with chapters at schools across the country. If other chapters adopt the swap-and-lock interface, they only have to design the socket that fits their recipient; the attachment library already exists.

Why Modular Worked for the Team, Too

The modular interface did two things beyond the user's needs:

  • It made delivery realistic. The socket and interface only had to be solved once, so the team could reliably get a working device to the user instead of betting everything on one complex hand.
  • It gave newer members a real project. With the interface fixed, a less experienced member could design a complete attachment on their own. That let me bring people onto the team with varying experience, teach CAD and design-for-printing on a scoped problem, and still produce parts the user could use.

What I Took Away

Most of the team were underclassmen, and membership changed from semester to semester. Leading it taught me to onboard people quickly and to give feedback in a way that pushed them to build better and keep learning. For many of them, Duke eNable was where they picked up CAD outside of class.

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